alloy round bar standard:Chinese GB,ASTM, DIN Material:a42CrMo,42CrMo4,4040 diameter: ... as bearing, gear, connecting rod, transmission gear, supercharger gear, engine cylinder, spring, 1200mm~2000mm rotary shouldered connections for petroleum industry, jar ... strength and larger size than 35CrMo. 42CrMo alloy steel round bar